Improvement of field emission performance on nitrogen ion implanted ultrananocrystalline diamond films through visualization of structure modifications

The relationship between the electron field emission properties and structure of ultra-nanocrystalline diamond (UNCD) films implanted by nitrogen ions or carbon ions was investigated. The electron field emission properties of nitrogen-implanted UNCD films and carbon-implanted UNCD films were pronouncedly improved with respect to those of as-grown UNCD films, that is, the turn-on field decreased from 23.2 V/μm to 12.5 V/μm and the electron field emission current density increased from 10E−5 mA/cm2 to 1 × 10E−2 mA/cm2. The formation of a graphitic phase in the nitrogen-implanted UNCD films was demonstrated by Raman microscopy and cross-sectional high-resolution transmission electron microscopy. The possible mechanism is presumed to be that the nitrogen ion irradiation induces the structure modification (converting sp3-bonded carbons into sp2-bonded ones) in UNCD films.

Research Highlights
► In this work, we present our findings and understandings in the field emission of UNCD films implanted by nitrogen ions with a possible mechanism for enhancing the field emitting properties.
► The UNCD films were modified structures on top parts of films by ion irradiation further to improve the field emission properties,
► and these films are extremely suitable for fabrication of UNCD-based cold cathode in flat panel displays and electron emitting devices.